Solid state electronic technology introduced an incredible reduction in the size of electronic devices. Integrated circuit technology now permits whole circuits to be placed on a thumb-nail size chip or wafer, and complex systems to be placed on a wafer only an inch or two in diameter. The small size of such integrated circuits promotes their use in many devices, especially in electronic watches.
Many electronic devices such as electronic watches also require displays for showing a function such as the time generated in the electronics. These display devices continue to require substantially greater electric power for their operation than is required for the operation of the integrated circuits.
Early displays required about 20 V.D.C. and over 1 microampere for their operation. Common power sources suitable for providing this high potential greatly exceeded the size of the integrated circuits and displays with which they were to be used and thereby encumbered the device in which the integrated circuit and display were incorporated; other suitable power sources were prohibitively expensive. To avoid these disadvantages, small electronic devices often included power sources providing a potential lower than that required by the display, but sufficient for the integrated circuitry, and electronic circuitry for multiplying the source potential to that required by the display. The prior art potential multipliers include both the transformer type of potential converter and the reactance type of converter. In both of these types, the size of the inductor and the number of auxiliary capacitors and bipolar transistors external to the integrated circuits causes the size and cost of the potential multiplying circuit to be excessive.
Other potential multiplying circuits for use in small electronic devices such as electronic watches are of the diode-capacitor network type. These networks are not practical because the potential drop across each diode is on the order of 0.5 to 0.7 V.D.C. while the available potential from a desirable power source such as a single dry cell is only about 1.5 V.D.C. While a higher potential power source would lessen the impractically high proportion of the source potential dropped across the diodes, such power sources are more expensive. Moreover, such circuits require a significant number of capacitors to which a corresponding number of connections from the integrated circuit must be made.
Therefore, it is desirable to minimize the number of capacitors required to be externally connected to the integrated circuit. Minimizing the number of capacitors also reduces the cost of the circuit. It is also desirable to minimize the number of other external connections required by the circuit.